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DOI: 10.1542/peds.109.3.e48
2002;109;e48Pediatrics
Richard L. Underhill and Marla Lewis
Timothy R. Schum, Thomas M. Kolb, Timothy L. McAuliffe, Mark D. Simms,
and Age Differences in Normal Children
Sequential Acquisition of Toilet-Training Skills: A Descriptive Study of Gender
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Sequential Acquisition of Toilet-Training Skills: A Descriptive Study of
Gender and Age Differences in Normal Children
Timothy R. Schum, MD*; Thomas M. Kolb, BS§; Timothy L. McAuliffe, PhD‡; Mark D. Simms, MD*;
Richard L. Underhill, BS§; and Marla Lewis, MEd储
ABSTRACT. Objective. To compare the ages, by gen-
der, at which normally developing children acquire in-
dividual toilet-training skills and to describe the typical
sequence by which children achieve complete toileting
success.
Methods. A longitudinal survey was conducted of a
cohort of children who were 15 to 42 months of age and
attending 4 pediatric practices in the Milwaukee area (2
inner city and 2 suburban) from 1995 through 1997. Par-
ents completed background surveys, and each child’s
development was assessed using the Bayley Scales of
Infant Development II. Each week for 12 to 16 months,
parents completed a training status survey (TSS). The
TSS, designed for this project, included information on
daily toilet-training status (eg, number of urine successes
on a 5-point scale) and 28 weekly toilet-training behav-
iors rated on a 5-point Likert scale from 1 (never) to 5
(always). Children were considered to have acquired a
particular skill when they received a rating of 4 or 5 on
the TSS scale. The median age and interquartile range for
children for each toilet-training skill are reported for
girls and boys separately using survival curve analysis.
Ages at which each gender achieved these skills are
compared using a log-rank test.
Results. The study included 126 girls and 141 boys;
88% were white. Parents submitted a total of 10 741
weekly surveys (range: 1–73; median: 49 per child). Girls
demonstrated toilet-training skills at earlier ages than
boys. The median ages for “staying dry during the day”
were 32.5 months (95% confidence interval: 30.9 –33.7)
and 35.0 months (95% confidence interval: 33.3–36.7) for
girls and boys, respectively. The median ages for readi-
ness skills for girls and boys, respectively, were as fol-
lows: “showing an interest in using the potty,” 24 and 26
months; “staying dry for 2 hours,” 26 and 29 months;
“indicating a need to go to the bathroom,” 26 and 29
months. There was a marked concordance in the se-
quences in which girls and boys achieve individual
skills. In addition, the interquartile ranges of the toilet-
ing skills varied from 6.9 to 11.4 months in girls and from
7.5 to 14.6 months in boys.
Conclusions. In this study population, girls achieve
nearly all toilet-training skills earlier than boys, includ-
ing successful completion. Most children do not master
the readiness skills until after the second birthday. The
range of normalcy for the attainment of individual skills
may vary by as much as a year. Pediatrics 2002;109(3). URL:
http://www.pediatrics.org/cgi/content/full/109/3/e48; toilet
training, gender, age, readiness, child development.
ABBREVIATIONS. FTTS, Fundamentals of Toilet Training Study;
TSS, training status survey; BSID-II, Bayley Scales of Infant De-
velopment II; SD, standard deviation; BM, bowel movement; CI,
confidence interval.
T
he medical literature on toilet training is woe-
fully deficient. Toilet training is a universally
acquired skill for normally developing chil-
dren, yet there is no information about the requisite
skills that children learn sequentially, beginning with
the signs of readiness and ending with successful
completion of toileting.
Current pediatric literature stresses the impor-
tance of the child’s readiness before initiating toilet
training.
1–3
Despite this perceived importance, a
commonly used developmental screening test in
general pediatrics does not reference any specific
toilet-training skills.
4
A critical review of the litera-
ture reveals 2 broad categories of readiness skills:
global readiness skills, which include achievement of
motor milestones (eg, sitting, walking), understand-
ing and use of words for elimination, positive rela-
tionships with caregivers and the desire to please,
identification with and imitation of parents and sig-
nificant others, and the desire to be autonomous and
master primitive impulses
2,5
; and specific toileting
readiness skills, which include bladder control (eg,
staying dry for 2 hours), physical awareness (eg,
appearing uncomfortable in soiled diapers), and in-
structional readiness (eg, indicating a need to uri-
nate).
3,6
Several authors have stated that these skills
are present by 18 to 24 months in normally develop-
ing children, yet normative data are lacking.
2,7
The broad sequence of achieving toileting “mile-
stones” has also varied across studies. For example,
Brazelton studied upper-middle-class children in
Cambridge, Massachusetts, and found that approxi-
mately 80% of children attained daytime control of
bowel and bladder function simultaneously at an
average of 28 months, with no difference between
the genders.
8
In 12% of children, daytime bowel
training occurred first; in 8%, bladder control was
achieved first. Stein and Susser
9
noted that children
who attended day nurseries in Lancashire, United
Kingdom, typically acquired nighttime bowel con-
trol before daytime control and daytime bladder con-
From the Departments of *Pediatrics and ‡Biostatistics, Medical College of
Wisconsin, Milwaukee, Wisconsin; §Kimberly-Clark Corporation, Neenah,
Wisconsin; and 储Children’s Service Society of Wisconsin, Waukesha, Wis-
consin.
Received for publication May 1, 2001; accepted Dec 3, 2001.
Reprint requests to (T.R.S.) Downtown Health Center Pediatric Clinic, 1020
N 12th St, Milwaukee, WI 53233. E-mail: tschum@mcw.edu
PEDIATRICS (ISSN 0031 4005). Copyright © 2002 by the American Acad-
emy of Pediatrics.
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trol before nighttime control. Largo and Stutzle
10
studied upper-middle-class Swiss children and also
noted that bowel control generally preceded daytime
and nighttime bladder control. Even different au-
thors in the same textbook have conflicting informa-
tion on the sequence of bowel versus bladder con-
trol.
1
However, the sequence of steps (specific toilet-
training skills including readiness skills) by which
children normally acquire these milestones has never
been studied in detail.
New information is needed because many fre-
quently cited references on toilet training are de-
cades old and the age at which children attain inde-
pendence in toileting has increased steadily during
the past century in industrialized countries for rea-
sons that remain elusive.
11–17
Studies of toilet train-
ing provide little insight on this trend because of
differences in sample composition, methods of train-
ing, cultural attitudes and beliefs, and definitions of
and criteria for “completion” of the process. How-
ever, a review of the available literature during the
past 50 years reveals a steady increase in age of
attainment of daytime bowel and bladder continence
from approximately 24 months in the 1950s to 36 to
39 months in the late 1990s.
8,11–17
Health care providers must have an evidence-
based understanding of the typical sequence and/or
stages of development to guide parents and profes-
sionals in the management of children with both
normal development and toileting-related difficul-
ties. Unfortunately, the lack of recent studies, data on
the typical sequence, and gender-specific differences
fail to provide a firm foundation to guide practice.
Ultimately at issue is accurate knowledge regarding
the process by which toilet training occurs so as to
determine which aspects of toilet training are influ-
enced by environmental factors (eg, educational
methods, parental expectations, different types of
diapers) and which are mostly “biological” and de-
pendent on physical maturation.
We undertook the Fundamentals of Toilet Training
Study (FTTS) to address the need for an evidence-
based understanding of toilet training. This study
addressed the following research question: What is
the age-specific chronology of toilet-training skills
among normally developing children by gender?
METHODS
Overall Study Design
The overall design of the FTTS involved 5 phases. Initially, the
recruitment phase included identification of interested parents of
age-appropriate children, followed by determination of eligibility
and obtaining informed consent. Then, parents filled out a mailed
survey describing child and parent demographics. Next, parents
returned to the clinic for an assessment of their child’s cognitive
development. The heart of the study was data gathering; parents
filled out a training status survey (TSS) detailing their child’s
toilet-training behaviors each week for 12 to 16 months. Finally,
data analysis was performed.
Participant Recruitment
Families were recruited into the FTTS (a descriptive longitudi-
nal study) between October 1995 and August 1996. For making the
results more generalizable, recruitment sites included 4 pediatric
clinics in the greater Milwaukee metropolitan area (2 inner city
clinics, whose populations are 60% Hispanic and 75% black, and 2
suburban clinics, whose populations are 70%–90% white). The
study families represented a convenience sample of parents who
responded to posters located in each clinic or were recruited by
word of mouth from clinic staff or doctors or fellow study parents.
Interested parents filled out an initial application. We made no
attempt to ascertain reasons that parents chose to participate.
Anecdotal reports, however, indicated that parents were often
interested in finding out about their child’s development or
wished to be part of a clinical research study. Within 3 weeks, a
research associate called each parent and administered a recruit
screening survey. In an effort to capture the entire toilet-training
process, we sought only those children who were not in toilet
training. Therefore, at recruitment, parents classified their child’s
toilet-training status as not started, not currently training, in train-
ing, or training complete. No additional explanation was provided
to the parent about these classifications, and no specific behaviors
were assigned. Parents of eligible children gave informed consent.
Inclusion/Exclusion Criteria
Children were eligible for the study if their toilet-training clas-
sification was either not started or not currently training, parents
planned to start toilet training within 3 months, and parents
agreed to send in a TSS each week for 1 year. Inclusion criteria
were child’s age between 15 and 40 months at the time of the
recruitment and English-speaking parent and child. The age range
was selected to include the most common ages for toilet training.
The upper age limit was chosen because the Bayley Scales of
Infant Development II (BSID-II) has a ceiling age of 42 months.
18
Exclusion criteria were child currently enrolled in a program for
developmentally delayed children, hospitalized for 10 or more
days in the previous year, or having a congenital problem with
bowel or bladder as these factors had the potential to delay the age
of successful toilet-training skills. Also excluded from the study
were children of parents who worked for an infant care product
company or families who had participated in more than 3 market
research studies involving diaper products in the last 6 months, as
both populations could influence the use of diapers and the toilet-
training process.
Sample
To achieve an enrollment goal of 300 participants, we obtained
initial applications from 1003 individuals. During the eligibility
screening process, 166 applications (17%) were rejected for the
following reasons: 95 applicants could not be reached and 71 (7%)
did not meet the inclusion criteria (25 were outside the age range,
20 had known developmental delay, 8 had frequent hospitaliza-
tions, 7 were involved in marketing research, and 11 others related
to inclusion/exclusion criteria). Of the eligible participants, 52
parents (5%) refused to participate (15 gave no reason, 14 for
parental scheduling conflicts, 23 for other reasons), 122 children
(12%) did not complete the scheduled developmental assessment,
16 children (2%) were excluded because no toilet-training status
was noted, and 380 children (38%) were already in toilet training
or their toilet training was complete, leaving 267 (27%) children in
the data set.
Demographic and Assessment Data
Child and parent demographic information was assessed using
a background survey tool. Child demographic information col-
lected included gender and age. Parental information surveyed
included age, race, marital status/living arrangement, parental
educational levels, hours per week each parent spent away from
home, household income, index child’s use of child care, and
number of other children the parents had toilet trained.
Child Cognitive Assessment
Each child’s cognitive development was assessed using the
BSID-II.
18
After formal training by the same pediatric psychologist
(including direct observation), 2 research associates, who were not
blinded to the study data, administered and scored the BSID-II
and verified information on the demographic surveys. BSID-II
scores were reported in the standard method with a mental de-
velopmental index (a numerical score having a mean of 100 and a
standard deviation [SD] of 15) and a descriptive classification of
delayed (⬍1 SD), average, or accelerated (⬎1 SD).
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Data Gathering, Survey Instrument, and Toilet-
Training Behavior
Weekly data collection occurred from October 1995 through
December 1997 with parents returning a weekly TSS for 12 to 16
months. Preliminary results revealed that more than half of the
children were still not toilet trained after participating for 12
months, so the weekly data collection was extended an additional
4 months for those children who were not daytime toilet trained
after 12 months. The FTTS TSS was developed, piloted, revised,
and used for this project. This survey tool asked parents to rate
their child’s behaviors on 28 different toilet-training behaviors, eg,
“stays dry during the day,” on a 5-point Likert scale (1 ⫽ never; 2,
3 ⫽ sometimes; 4, 5 ⫽ always) for that week. Twenty-six of the
skills were common to both genders, and 1 skill was specific to
each gender (“wipes urine effectively” for girls and “urinates
while standing” for boys). We included the skill of “has a potty
chair available,” although it is more a parental behavior because it
reflects a readiness of the parents to initiate toilet training. To
anchor selected behaviors, parents rated the child in the following
categories: number of accidents per day, number of times the child
sat on the potty per day, and number of urine successes per day
using a 5-point Likert scale and number of bowel movements
(BMs) per day using a 4-point Likert scale.
The Human Rights Review Board at Children’s Hospital of
Wisconsin and the Human Research Review Committee of the
Medical College of Wisconsin approved the entire protocol. Par-
ents were reimbursed for their efforts after the initial developmen-
tal assessment, monthly and at the end of the study.
Outcome Measures and Statistical Analysis
The age at attainment of a specific toilet-training skill was
calculated as the child’s age at the week when the parent first
rated the child’s behavior as 4 or 5 for performing that skill.
Categories 4 and 5 were grouped together because they indicated
a reasonable mastery of that skill. For children who did not master
a skill before the conclusion of the study, the age at attaining the
skill is known only to be beyond their age at the end of the study
period. In this case, the child’s age at end of the study period was
calculated and recorded as a censored measure of the exact age at
attainment. Because for several skills, some children did not mas-
ter the skills before the conclusion of the study period, the Kaplan-
Meier method for estimating survival curves with censored data
were used to estimate the 25th percentile, median, and 75th per-
centile of the age distribution for achievement of each skill. The
log-rank test was used to compare age distribution at attainment
of a skill.
The correlation between the Bayley mental index, use of child
care, and the presence of siblings with the behavior “enters bath-
room and urinates by self” stratified by gender was analyzed
using repeated measures logistic regression.
To provide a behavioral anchor for our weekly toilet-training
status items, we did a correlation between the daily behaviors of
“number of accidents,”“sits on potty,”“urinates in potty,” and
“has a BM in potty” with the weekly behavior of “stays dry for 2
hours.” Because each child has a number of weekly status reports,
violating the assumption of independent observations, the corre-
lation was done for each child first. The resultant nonparametric
Spearman rank correlations were then summarized using the me-
dian and central interval excluding the lower 5% and upper 95%.
P values were not as helpful because the large sample size makes
small correlations significant. The statistical software SAS (Ver-
sion 8.0; SAS Institute, Inc, Cary, NC) was used for analysis, and
statistical test significance was set at the .05 level.
RESULTS
The demographics of the study population are
presented in Table 1. Participating families returned
10 741 weekly training status surveys (mean: 40.2;
median: 49; range: 1–73).
For the girls, the mean age at the start of the study
was 23 months. The girls’ median ages and the in-
terquartile ages (the ages when 25% vs 75% of the
children acquired the skill) rank ordered by the me-
dian ages for each of the 27 skills are shown in Fig 1.
On average, the earliest skill to emerge for girls was
“stays BM free at night” (22.1 months), whereas the
latest skill acquired was “wipes poop effectively”
(48.5 months). The median ages, confidence intervals
(CIs), and the number of girls who acquired that skill
are shown in Table 2. The median age when parents
rated their girls as “stays dry during the day” was
32.5 months (95% CI: 30.9 –33.7). The median age
when girls could independently enter the bathroom
and urinate by themselves was 33.0 months (95% CI:
31.2–34.4). The interquartile ranges varied from 6.9 to
11.4 months for girls for the age at acquiring each
skill. There were not enough children who attained
the skill of “wipes poop effectively” to be able to
determine the 75th percentile for girls or boys.
For boys, the mean age at the start of the study was
25 months. The boys’ median ages and the interquar-
tile ages for each of the 27 skills are shown in Fig 2.
On average, the earliest skill to emerge for boys was
“understands potty words” (24.5 months), whereas
the latest skill acquired was “wipes poop effectively”
(45.1 months). The median ages, CIs, and the number
of boys who acquired that skill are shown in Table 2.
The median age when parents rated their boys as
“stays dry during the day” was 35.0 months (95% CI:
33.3–36.7). The median age when boys could inde-
pendently enter the bathroom and urinate by them-
selves was 37.1 months (95% CI: 35.0–38.6). The in-
terquartile ranges varied from 7.5 to 14.6 months for
boys for the age at acquiring each skill.
The median ages, CIs, and significance levels com-
paring girls and boys for each of the 28 skills are
TABLE 1. Profile of Study Population
Group n (%)
Children
Number of children 267
Boys 141 (53)
Girls 126 (47)
Race
Black 16 (6)
White 236 (88)
Other 15 (5)
Child care use 101 (38)
Siblings at home
None 81 (30)
1 or more 186 (70)
BSID-II Mental Developmental
Index (mean ⫾ SEM)
103.4 ⫾ 6.3
Parents
Parental status
Both living with child 246 (92)
One living with child 20 (8)
Household income
ⱖ$50 000 126 (49)
⬍$50 000 129 (51)
College degree
Mother 141 (53)
Father 142 (55)
Employed
Mother 168 (61)
Father 251 (99)
Mean work time per wk (h)
Mother 20.9
Father 46.2
Mean age (y)
Mother 30.8
Father 33.4
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presented in Table 2. Overall, girls attained toilet-
training skills at younger ages than boys in all cate-
gories except “flushes toilet by self” and “washes
hands by self.” The 1 skill in which boys achieved
success at an earlier age was “wipes poop effectively
by self.” The skills that showed the greatest differ-
ences in median ages between girls and boys were
“enters bathroom and has a BM by self” and “sits on
potty when placed for 5 minutes” at 5.0 and 4.5
months, respectively.
There was a marked concordance between the
girls and boys in the order in which the 26 skills
common to both genders are attained. Only 2 skills
showed a rank order difference of 3 positions be-
tween the girls and boys: flushes toilet by self (10th
for girls and 6th for boys), although the median ages
varied by only 0.2 months, and tells during or after
urinating (11th for girls and 14th for boys), for which
median ages varied by 4.2 months. There was no
correlation between the Bayley mental index, pres-
ence of siblings, or the use of child care with the
outcome “enters bathroom and urinates by self” for
either girls or boys.
The correlation between the daytime behaviors of
number of accidents, times sitting on the potty, uri-
nations in the potty, and BMs in the potty with the
weekly skill of “stays dry for 2 hours” is shown in
Table 3. As the ratings for “stays dry for 2 hours”
increased, the median ratings for 3 of the 4 daytime
behaviors increased, whereas the number of acci-
dents per day decreased.
DISCUSSION
This is the first study to document the sequential
acquisition of the entire range of toilet-training skills
in normally developing children. As has been noted
in some previous studies of toilet training, we found
that girls acquire specific skills at earlier ages than
boys in almost every category.
8,15,16,19
One obvious
explanation is that girls’ physical and language skills
mature sooner than boys’. Another explanation is
that parents may initiate toilet training girls at
younger ages than boys, and the practice at an earlier
age leads to earlier acquisition of skills.
Contemporary literature has maintained that toi-
leting readiness skills typically develop between 18
and 24 months of age.
1–3
Our data challenge this
conventional wisdom. In only 2 of the 11 readiness
skills were the median ages for girls less than 24
months of age: “stays BM free overnight” (22.1
months) and “understands potty words” (22.8
months). The median ages for boys were over 24
months in all 11 readiness criteria. Although some
boys and girls acquire readiness skills before their
second birthday, most do not. As practitioners advo-
cating that parents wait until their children are ready
to start toilet training, we should now revise our ages
upward to 22 to 30 months when children are typi-
cally ready for toilet training.
The marked concordance in the sequence of attain-
ing toilet-training skills between girls and boys
should help providers to counsel parents about ex-
pected norms for children to master toilet-training
Fig 1. Age of attaining toilet-training skills— girls.
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skills. Early toileting skills tend to be readiness skills:
“understands potty words,”“shows an interest,”
“tells during or after having a bowel movement,”
“stays dry for 2 hours,” and “indicates a physical
need to go.” Middle toilet-training skills involve
many self-help skills that can be taught to children:
“flushes toilet by self,”“washes hands,” and “pulls
training pants up and down.” Late toilet-training
skills show major strides in toilet-training comple-
tion: “uses a regular toilet,”“stays BM free during
the day,”“tells before having to urinate,”“stays dry
during the day,”“enters bathroom to urinate or have
aBM,” and “stays dry overnight.”
Our data add to the current information about the
sequence of bowel and bladder control. Nighttime
bowel control is an early toilet-training skill, whereas
nighttime urine control is one of the last skills to
develop for both genders. Although girls achieve
daytime bowel and urine control at younger ages
than boys, there is no statistically significant differ-
ence between the ages at attainment of daytime
bowel control versus daytime urine control within
each gender. Interquartile ranges vary from 7.9 to
12.3 months for the 4 skills and are especially notice-
able in the skill of “waking up dry overnight” for
which the interquartile range is 9 months for girls
and 12 months for boys. The considerable overlap in
the ages at acquiring daytime bowel and urine con-
trol helps to explain the wide variation in individual
acquisition of skills and accounts for the conflicting
reports in the literature.
1,8,10
The reasons for the wide interquartile ranges of
ages in acquiring the skill “enters bathroom and
urinates by self” remain elusive. Our study shows
that developmental ability among normal children is
not critical. Even parental experience with a previous
sibling was not predictive. Parents can be reassured
that child care use does not seem to affect the acqui-
sition of toilet-training skills as also noted by oth-
ers.
15,16
At present, we are not able to predict which
child will toilet train at a younger age.
Our study has several limitations, including 3 for
the outcome measure. First, outcome measures rely
on parental report of a global score. As with other
rating scales, there can be variability in which rating
each parent may assign to particular behaviors. Sec-
ond, behavioral anchors are not assigned to a partic-
ular rating for each skill achievement. However, Ta-
ble 3 shows that the correlation between 4 behaviors,
eg, the number of successful urinations in the potty
with “stays dry during the day,” is excellent. Third,
some children entered our study at young ages and
may not have even reached the ages for the 75% for
some of the skills. Another limitation is that the
parents of our study children were highly educated,
affluent, and mostly of white race. We had difficulty
recruiting minority children. One reason was that
many black children were already in the process of
toilet training by 15 months of age, our lower age
limit. Minority children successfully achieve toilet
training at earlier ages,
16,19
so it is reasonable to
assume that they would acquire specific toilet-train-
ing skills at earlier ages than white children. Addi-
TABLE 2. Ages of Attaining Toilet-Training Skills by Gender
Toilet-Training Skill Girls Boys P
Value
Median Ages
(Months)
95% CI
(Months)
n Median Ages
(Months)
95% CI
(Months)
n
Stays BM free overnight 22.1 20.7–24.3 123 24.7 23.0–25.5 135 .007
Understands potty words 22.8 21.4–24.0 125 24.5 23.3–25.8 133 .002
Has potty chair/seat available 23.2 22.0–24.4 115 25.2 24.2–26.2 126 .002
Shows interest in using the potty 24.1 22.9–24.9 118 26.2 24.8–27.6 125 .012
Tells during or after having a BM 24.6 23.0–26.3 118 27.0 25.2–28.7 123 .0007
Has regular BMs 24.9 23.5–26.5 105 26.2 24.4–30.5 107 .044
Stays dry for over 2 hours 26.0 24.0–27.3 112 28.9 27.8–31.6 119 .0002
Indicates the physical need to go to the bathroom 26.3 24.5–27.2 109 29.3 26.7–30.9 111 .003
Sits on potty when placed for 5 minutes 26.7 25.3–28.3 106 31.2 28.3–33.3 105 .0001
Flushes the toilet by self 26.8 25.8–28.5 104 27.0 25.6–28.7 123 NS
Tells during or after peeing 28.4 26.3–29.3 108 32.6 30.4–33.6 105 .0001
Knows how to urinate in the potty 28.8 26.6–30.4 104 30.9 29.0–32.1 113 .009
Washes hands by self 29.4 28.4–30.8 95 31.7 29.4–33.2 100 NS
Pulls training pants or underwear up by self 29.5 28.4–30.8 96 33.5 32.2–34.1 106 .0001
Urinates in potty with help 29.7 27.7–31.2 102 31.7 29.4–33.5 107 .003
Pulls training pants or underwear down by self 29.7 28.9–30.7 98 32.8 31.4–34.1 107 .0005
Wears training pants or underwear 30.9 30.2–32.4 97 33.8 32.4–35.7 107 .0001
Tells before having a BM 31.0 28.7–33.5 92 33.6 31.8–35.7 98 .01
Uses regular toilet without a potty seat 31.4 29.2–32.8 96 34.0 32.6–35.7 99 .0002
Stays BM free during the day 31.5 30.0–33.3 96 34.7 33.6–36.5 97 .0004
Tells before having to urinate 31.9 30.8–33.3 91 34.7 33.3–36.7 91 .0006
Wipes urine effectively by herself 32.2 29.5–33.3 85 NA NA NA NA
Urinates while standing by himself NA NA NA 38.0 35.6–39.3 77 NA
Stays dry during the day 32.5 30.9–33.7 92 35.0 33.3–36.7 98 .002
Enters bathroom and urinates by self 33.0 31.2–34.4 82 37.1 35.0–38.6 85 .002
Wakes up dry overnight 34.1 31.9–35.8 80 35.8 33.5–37.8 86 .03
Enters bathroom and has BM by self 34.4 33.5–35.8 78 39.5 37.8–40.4 69 .0001
Wipes poop effectively by self 48.5 * 37 45.1 * 31 .01
NS indicates not significant; NA, not applicable.
* Unable to determine.
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tional research is needed to evaluate black children
but must focus on children younger than 15 months.
The findings represent an American approach, as
children are toilet trained at younger ages in other
cultures.
17,21,22
Also, even with 267 children enrolled,
compliance in returning weekly reports was not per-
fect. We had 2 groups of families. Some were excep-
tional at returning surveys with half sending in more
than 50 surveys, whereas 15 families sent in fewer
than 10 weekly surveys. Finally and curiously, the
category of number of accidents per day created
some unanticipated difficulty. Many parents be-
lieved that an accident occurs only when children are
out of diapers, so the number of accidents did not
turn out to be a reliable indicator early in the toilet-
training process.
CONCLUSION
Pediatricians should continue to emphasize the
importance of readiness for the initiation of toilet
training. The ages when children achieve typical
readiness skills, now in the range of 22 to 30 months,
is older than previously reported. We now have in-
formation about the usual sequence that children
follow along the toilet-training continuum, so prac-
titioners can provide normative data and counsel
parents of children who are having toilet-training
difficulty. It is hoped that additional research will
lead to a toilet-training progress scale that can be
used both to assess where a child is along the toilet-
training continuum at any given time and to com-
pare data from different research studies. In addi-
Fig 2. Age of attaining toilet-training skills— boys.
TABLE 3. Mean Daily Occurrence Rate for Various Toilet-Training Behaviors by Weekly Frequency of Staying Dry for at Least 2
Hours at a Time—Spearman Correlation Over Each Child’s Multiple Weekly Status Reports (Median and Outer 5% Ranges)
Toileting Behaviors Stays Dry for at Least 2 Hours Spearman Correlation
Never
(1)
Seldom
(2)
Sometimes
(3)
Mostly
(4)
Always
(5)
Median‡
Correlation
5th and 95th
Percentiles
Number of accidents* 3.4 3.1 2.7 2.0 1.2 ⫺0.48 ⫺0.94 to ⫺0.22
Sits on potty* 1.9 2.3 2.8 3.6 3.4 0.39 ⫺0.25 to 0.83
Urinates in potty* 1.5 1.9 2.5 3.5 3.5 0.52 ⫺0.18 to 0.87
Has BM in potty† 1.1 1.3 1.5 2.0 2.1 0.42 ⫺0.15 to 0.87
* Scale: 1 ⫽ zero, 2 ⫽ one to two, 3 ⫽ three to five, 4 ⫽ six to eight, 5 ⫽ nine or more.
† Scale: 1 ⫽ zero, 2 ⫽ one, 3 ⫽ two, 4 ⫽ three or more.
‡ Median correlation among participants between toileting behaviors and weekly status for “stays dry for at least 2 hours,” over the course
of study for an individual’s repeated weekly status assessments.
6of7 AGES AT ACQUISITION OF TOILET-TRAINING SKILLS BY GENDER
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tion, research is needed to examine the natural
history of how rapidly children progress once ac-
tively in toilet training, which techniques are most
effective in helping children acquire toilet-training
skills, and what influences racial differences in toilet
training.
ACKNOWLEDGMENTS
This study was funded by a grant from the Kimberly-Clark
Corporation (Neenah, WI) in conjunction with the Medical Col-
lege of Wisconsin.
We thank the physicians and staff at Pediatric Consultants,
Southwest Pediatrics, 16th Street Community Health Center, and
the Downtown Health Center Pediatric Clinic; Drs Michael
Chusid, Patricia Lye, Karen Marcdante, David Schiedermayer,
Deborah Simpson, and Rebekah Wang-Cheng for manuscript re-
views; Ron Pupp for research support; and Gail Kreklow for
secretarial assistance.
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DOI: 10.1542/peds.109.3.e48
2002;109;e48Pediatrics
Richard L. Underhill and Marla Lewis
Timothy R. Schum, Thomas M. Kolb, Timothy L. McAuliffe, Mark D. Simms,
and Age Differences in Normal Children
Sequential Acquisition of Toilet-Training Skills: A Descriptive Study of Gender
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